A poorly written OS for the x86 arch. (WIP)
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eOS/drivers/vga.c

69 lines
1.4 KiB

// VGA Graphics Library
#include "../kernel/io.h"
// Memory
#define VGA_ADDRESS (char*)0xb8000
#define VGA_ADDRESS_MAX (char*)0xb8fa0
#define MAX_ROWS 25
#define MAX_COLS 80
static unsigned int cursor_row = 0;
static unsigned int cursor_col = 0;
/*
VGA & Memory Functions
*/
char* get_vga_charpos_pointer(unsigned int col, unsigned int row) {
return (char*)(VGA_ADDRESS + 2*((row*80) + col));
}
void writechar(char c, unsigned int col, unsigned int row, int attribute_byte) {
if( !attribute_byte )
attribute_byte = 0x0f;
char* mem = get_vga_charpos_pointer(col, row);
*mem = c; // Write the character
*(mem+1) = attribute_byte; // Write the attribute_byte
}
void set_cursor_pos(unsigned int x, unsigned int y) {
cursor_col = x;
cursor_row = y;
}
/*
Graphics Functions
*/
void clear_screen() {
for( int c = 0; c < MAX_COLS; c++ )
for( int r = 0; r < MAX_ROWS; r++ )
writechar(0x20, c, r, 0xf0);
}
void disable_vga_cursor() {
port_outb(0x0a, 0x3d4);
port_outb(0x20, 0x3d5);
}
/*
General Printing Functions
*/
void print(char* str, int attribute_byte) {
for( char* c = str; *c != '\0'; c++ )
writechar(*c, (unsigned int)(c - str) + cursor_col, cursor_row, attribute_byte);
}
void println(char* str, int attribute_byte) {
print(str, attribute_byte);
cursor_row++; // Increment to next y-pos (newline)
}
// VGA Initialization Function
void vga_init() {
disable_vga_cursor();
clear_screen();
}